Method of removing coke deposits from high-temperature oil lines



Jgn. 2,` 1945.

J. J. GulcHE-r 2,366,521

METHOD OF REMOVING COKE DEPOSITS FROM HIGH-TEMPERATURE OIL LINES FiledFeb.' 25, 1943 i Patented Jan.2; 1945 METHOD on REMovING `corna;ffnerosrrs V`IFROM HIGH-TEMPERArURELoIL-IL'INES "JlulesLJ- GilichetBatonRouge, La-, assigner Qto n Standard :Oil `Develop'l'nentCompany, a c orpon n l I `ration of Delaware.` n

Appiioanon Ireblrluaryza 1943,;seria1iNo. 47790418 I f 3 Claims. Il.1961-69) In This invention `relates toagmethod ofrmoving coke depositsfrom high-rtemperature oil lines and pertains lmoreparticularly to amethod `of removing coke deposits l formed duringhigh--temtion withinthe separator. Unvaporized residue is removed from-the bottom of theseparator I5 lthrougfhline II'I. I I; I

Vapors liberatedin the `separator I5 .compris- Y ing uvaporized IoilItogether I with an. substantial perature cracking of hydrocarbonroilsgforwthe 55 amount of steam are removed overheadfrom the productionof `oleinic gases.` n `separator I,5througl1 line I8 and are; charged to`It has been the practicegto crack various oil alcracking coil-locatedina furnace I9 in which n If'racgtions, such as .gas .oil,I Vkerosene4andIlig-hter the -oil 'is rapidly heated to the desired reaction @il orhydrocarbon gases,`atV high temperatures, temperature. In cases wherethecharging stock Suchas temperaturesfof the lorderlof from 1100" .Ellotoithefheating coil I2 comprises a clean VaporizliO .l.400 F2, toproduce ,oleiinic constituents, ableoil, theseparator l5 may bevomitted,orI the gsuchaslethylene, propylene, butadiene, and the products `fromI`the heating 4coil I2 maybe bylikefWl-lichmayginfturn formstartingmaterials -passedthrough -line 2I directly to thecrackingforftheIproduction of other products. 4Following coil I9. ,In theproduction of olenic gases as theIcrackingtreatment,it has been` thepractice previously mentioned, the oil is subjected in the to-quench thecracked products below Iactive recracking coil III9 Ito temperatures ofthe order of @dion-temperature, suchasbelow 500l'. to 606 'n from1100F.to 1400\-F., preferably between I F., `'prior Vtofsubjecting thecracked Amaterial to 1200 `and 1300\F. The oil is maintainedfractionation and segregation. withinA the cracking coil I9 for a periodsuflcient ,It,1hasbeenfound thatwhen crackingoils in 20 toconvertagsubstantial.portion thereofIinto-Iolethis manner, rockingdiiculties `areencountei-'ed nic "gases, :such as ethylene, prop ylene,butyl- :the `I-egon Wherethe quenching liquidis inn enes andethelike.` lIn Y n `z troducedintoItheoillstream.` 4fIhesejcoking ,dif- The cracked`products are yremoved fromIthe 4iulties-grequire frequent interruptionof Ithe op cracking coil I9"thro`ugh Ia transfer line 22 into erationtoremove the flcoke. I I "1125 which aquenching liquidsuch as an oilorwater The principalobject ofIthepresent.invention` istintroducedflOmline 23. I n I is to "provide a `methodgof 1reducingfithe poking Inaccordance withythe present invention, this diiliculties just mentioned.I quenching liquid is first `introduced into the 'I'heabove and otherobjects of the invention (,g transfer Iline22 through line 24 at a pointadja- .will beapparent'fromithe"y more detailedIdescrip- 50 cent theoutlet nof thecrackingIcoil. The-introtion hereinafter-finwhiohreference will ,be made duction of the `quenching `liquid into :the hot,to the accompanying `drawing which is a diagaseous products removedfrornthe cracking..coil granuli.atcillustration` of equipment for high- I9tends to form carbonaceous `deposits :in the I temperature cracking inwhich the present in region immediately adjacent the point ofintrovention nds particular application. 35 duction of the quenchingliquid. The quenching Referring to the drawing, the reference charliquidis introduced through line 24 into the acter I0 designates a charge linethrough which transfer line 22 until a substantial amount of `the oil tobe processed is introduced into the coke deposits is formed. The pointof introducequipment. This `oil may comprise a crude petion of thequenching liduid is shifted from 5 troleum or a selected fractionthereonsuch as a `40 to 10 feet further downstream. As illustrated,gasoil, kerosene or, in some cases, hydrocarbon the quenching liquidpassing through line 24 may gases. The oil introduced through line II)is be discontinued and the quenching liquid introcharged by means ofpump I I to a vaporizing duced through branch line 25. The introductionfurnace I2 in which the oil is heated to vaporize of the quenchingliquid through line 25 into the a substantialportion thereof.High-temperature 45 transfer line is continued until the temperature Isteam may be introduced through lineII3 at one at the original point ofintroduction of the or more spaced points within the vaporizing coilquenching liquid has been materially increased. to assistV thevaporization thereof. The oil after The increase in temperature at thepoint of inpassing through the vaporizing furnace I2 is troduction ofthe initial quenching oil through transferredthrough line I 4 to aseparator II5 in 50 line 124 tends to expand the transfer line 22 andwhich vaporized constituents are separated from thereby loosencarbonaceous `deposits adhering unvaporized residue. Additional steamImay be thereto. 'I'he carbonaceous deposits so loosened passed throughline I6 into the bottomportion `are then carried out of thetransfer line22 by of the separator to assist further in the vaporiza-` u the oilstream into a fractionating tower 26 from 21.

which they may be withdrawnthrough line After the carbonaceous depositshave been removed, the quenching liquid is again introduced through line24. In other words, during the main portion of the operating period, thequenching procedure that the lengths of operating runs be- V tweenshutdowns for removing coke deposits have in some cases been increasedfivefold. vThis reduction in the number of shutdowns required forcleaning the equipment represents a material saving and increases theannual productive capacity ofthe cracking plant.

The cracked products after passing through the transfer line 22discharge into a fractionating tower 26 wherein the products aresubjected to fractionation to condense constituents boiling above themotor fuel boiling range. Condensate formed in the fractionating tower26 is removed trom the bottom thereof through line 21. This condensatemay be removed from the system through line 28, lor a part of it may bepassed through line 29, cooler 3| and pump 32. and utilized as aquenching medium. Vapors remaining uncondensed in the fractionatingtower 2B are removed overhead through line 33 to a condenser 34 in whichthe normally liquid constituents boiling in the motor fuel boiling rangeand steam are condensed. Products from the condenser 313 may be thenpassed tol a low-pressure product receiver 35 in which liquid distillatecondensed in the condenser'34 is separated from the gaseous products.Steam distillate may be removed from the bottom of the low-pressurereceiver 35 through line 36. Gaseous products separated from liquiddistillate in product receiver 35 may be passed through line 31 tosuitable equipment for separation of the olenic constituents therefrom.The liquid oil distillate separated from the water condensate andgaseous products in receiver 35 may be removed as a side stream throughline 38.

Having described the preferred embodiment of 'the invention, it will 4beunderstood that it embraces such other variations and modifications ascome within the spirit and' scope thereof.

What is desired to be protected by Letters Patent is:

1. In a process for the high-temperature conversion of hydrocarbon oilswherein a quenching medium is introduced into a stream of conversionproducts passing through a conduit following the conversion treatmentand wherein solid deposits tend. to accumulate within the conduit in theregion adjacent the point of introduction of said quenching medium; themethod of removing said solid deposits which comprises introducing thequenching medium into the stream of conversion products at apredetermined point,` continuing the introduction `of said 'quenchingmedium at said point until a substantial amount of solid deposits isformed in the region adjacent said point of introduction, thereafterdiscontinuing the introduction of the quenching medium at said point,

introducing the quenching medium a substantial distance downstream fromsaid rst-named point, continuing the introduction of the quenchingmedium downstream from said first-named point for a limited period onlysufficient to increase the temperature of the conduit at saidrst-namedpoint and loosen the solidiv deposits, and immediately thereafter againintroducing the quenching medium at said first-named point.

2. In a process for cracking hydrocarbon oils to form olenic gaseswherein the oil is subjected to cracking conditions of the ordery offrom 1100" F. to 1400 F. and wherein a quenching medium is introducedinto a stream` of cracked products passing through a conduit following.the

cracking treatment; the method of removing coke deposits formed at thepoint of introduction of .said quenching medium which comprisesintroducing the quenching medium into a stream of cracked products at apredetermined point, continuing` the introduction of the quenchingmedium at said point until a substantialA amount of solid deposits isformed in the region adjacent the point of introduction, thereaftershifting the point of introduction of the quenching medium a substantialdistance downstream from said rstv. named point, continuing theintroduction of the quenching medium at said last-named point for alimited period suflicient only toincrease the temperature of the'conduitadjacent the first-named point and to loosen solid deposits formedtherein, and immediately thereafter returning the quenching medium tosaid first-named point.

3. Thev process dened in claim 2 wherein the quenching medium is ahydrocarbon oil.

JULES J. GUICHET.

